I don't know if they charge for online or not. I've never been compelled to try it, as the game by itself is fun enough. I play co-op with my roommate and we have a good time.
XBOX: been using it to watch season 1 of Popular PS2: Katamari Damacy Gamecube: Switching between Tales of Symphonia and Donkey Konga GBA: Castlevania: Aria of Sorrow